Helleborus plant named ‘COSEH 4500’

ABSTRACT

A new and distinct cultivar of  Helleborus  plant named ‘COSEH 4500’, characterized by its upright and mounding plant habit; uniform and freely flowering habit; dark green-colored leaves; freely and early flowering habit; single white-colored flowers; and good garden performance.

Botanical designation: Helleborus×ericsmithii×Helleborus×hybridus.

Cultivar denomination: ‘COSEH 4500’.

CROSS-REFERENCED TO CLOSELY-RELATED APPLICATIONS

Title: Helleborus Plant Named ‘COSEH 4100’

Applicant: Josef Heuger

Filed: Concurrently with this application having application Ser. No. 14/999,209

Title: Helleborus Plant Named ‘COSEH 4200’

Applicant: Josef Heuger

Filed: Concurrently with this application having application Ser. No. 14/999,210

BACKGROUND OF THE INVENTION

The present invention relates to a new and distinct cultivar of Helleborus plant, botanically known as Helleborus×ericsmithii×Helleborus×hybridus and hereinafter referred to by the name ‘COSEH 4500’.

The new Helleborus plant is a product of a planned breeding program conducted by the Inventor in Glandorf, Germany. The objective of the breeding program was to create new uniform Helleborus plants with unique and attractive plant habit, leaf and flower coloration and resistance to pests common to Helleborus plants.

The new Helleborus plant originated from a cross-pollination conducted by the Inventor in Glandorf, Germany in February, 2011 of a proprietary selection of Helleborus×ericsmithii identified as code number HE 10843, not patented, as the female, or seed, parent with an unnamed seedling selection of Helleborus×hybridus, not patented, as the male, or pollen, parent. The new Helleborus plant was discovered and selected by the Inventor as a single flowering plant from within the progeny of the stated cross-pollination grown in a controlled greenhouse environment in Glandorf, Germany in November, 2012.

Asexual reproduction of the new Helleborus plant by divisions in a controlled environment in Glandorf, Germany since March, 2013 has shown that the unique features of this new Helleborus plant are stable and reproduced true to type in successive generations.

SUMMARY OF THE INVENTION

Plants of the new Helleborus have not been observed under all possible combinations of environmental conditions and cultural practices. The phenotype may vary somewhat with variations in environmental conditions such as temperature and light intensity without, however, any variance in genotype.

The following traits have been repeatedly observed and are determined to be the unique characteristics of ‘COSEH 4500’. These characteristics in combination distinguish ‘COSEH 4500’ as a new and distinct Helleborus plant:

-   -   1. Upright and mounding plant habit.     -   2. Uniform and freely flowering habit.     -   3. Dark green-colored leaves.     -   4. Freely and early flowering habit.     -   5. Single white-colored flowers.     -   6. Good garden performance.

Compared to plants of the female parent selection, plants of the new Helleborus and the female parent selection differ primarily in flower color as plants of the female parent selection have creamy white to pink-colored flowers. Compared to plants of the male parent selection, plants of the new Helleborus are more uniform and are more freely flowering.

Plants of the new Helleborus can be compared to plants of Helleborus×ericsmithii×Helleborus×hybridus ‘COSEH 4100’, disclosed in a U.S. Plant Patent application filed concurrently having application Ser. No. 14/999,209, and Helleborus×ericsmithii×Helleborus×hybridus ‘COSEH 4200’, disclosed in a U.S. Plant Patent application filed concurrently having application Ser. No. 14/999,210. Plants of the new Helleborus differ primarily from plants of ‘COSEH 4100’ and ‘COSEH 4200’ in flower color as plants of ‘COSEH 4100’ have red purple to grayed purple-colored flowers and plants of ‘COSEH 4200’ have pink-colored flowers.

Plants of the new Helleborus can also be compared to plants of Helleborus niger ‘COSEH 700’, disclosed in U.S. Plant Pat. No. 21,003. In side-by-side comparisons, plants of the new Helleborus differ primarily from plants of ‘COSEH 700’ in flower color as plants of ‘COSEH 700’ have light green-colored flowers tinged with reddish overtones.

BRIEF DESCRIPTION OF THE PHOTOGRAPHS

The accompanying colored photographs illustrate the overall appearance of the new Helleborus plant showing the colors as true as it is reasonably possible to obtain in colored reproductions of this type. Colors in the photographs may differ slightly from the color values cited in the detailed botanical description which accurately describe the colors of the new Helleborus plant.

The photograph on the first sheet is a side perspective view of a typical flowering plant of ‘COSEH 4500’ grown in a container.

The photograph on the second sheet is a close-up view of a typical flower of ‘COSEH 4500’.

DETAILED BOTANICAL DESCRIPTION

The aforementioned photographs and following observations, measurements and values describe plants grown during the autumn and winter in 13-cm containers in a glass-covered greenhouse in Glandorf, Germany and under cultural practices typical of commercial Helleborus production. During the production of the plants, day temperatures ranged from 12° C. to 32° C. and night temperatures ranged from 3° C. to 18° C. Plants were 16 months old when the photographs and the description were taken. In the following description, color references are made to The Royal Horticultural Society Colour Chart, 2015 Edition, except where general terms of ordinary dictionary significance are used.

-   Botanical classification: Helleborus×ericsmithii×Helleborus×hybridus     ‘COSEH 4500’. -   Parentage:     -   -   Female, or seed, parent.—Proprietary selection of             Helleborus×ericsmithii identified as code number HE 10843,             not patented.         -   Male, or pollen, parent.—Unnamed seedling selection of             Helleborus×hybridus, not patented. -   Propagation:     -   -   Type.—By tissue culture.         -   Time to initiate roots, winter.—About two months at             temperatures about 12° C.         -   Time to produce a rooted young plant, winter.—About six             months at temperatures ranging from 4° C. to 15° C.         -   Root description.—Thick to thin, fleshy; typically white to             brown in color, actual color of the roots is dependent on             substrate composition, water quality, fertilizer type and             formulation, substrate temperature and physiological age of             roots.         -   Rooting habit.—Sparse. -   Plant description:     -   -   Plant and growth habit.—Herbaceous perennial; upright and             mounding plant habit with flowers held above and beyond the             foliar plane; plant shape, roughly flattened globular;             moderately vigorous growth habit; moderate growth rate.         -   Plant height, soil level to top of foliar plane.—About 24             cm.         -   Plant height, soil level to top of flowers.—About 33.6 cm.         -   Plant diameter (area of spread).—About 50.5 cm. -   Leaf description:     -   -   Arrangement.—Leaves arranged in a basal rosette; leaves             palmately compound with typically five, or occasionally             seven, leaflets per leaf.         -   Leaf length.—About 24.9 cm.         -   Leaf width.—About 24.9 cm.         -   Leaflet length.—About 16.1 cm.         -   Leaflet width.—About 7.4 cm.         -   Leaf shape.—Palmate; reniform in outline.         -   Leaflet shape.—Ovate, elliptic and obovate.         -   Leaflet apex.—Apiculate.         -   Leaflet base.—Attenuate.         -   Leaflet margin.—Serrate; slightly undulate.         -   Leaflet texture and luster, upper surface.—Smooth, glabrous;             slightly rugose; leathery; glossy.         -   Leaflet texture and luster, lower surface.—Smooth, glabrous;             slightly rugose; leathery; moderately glossy.         -   Leaflet venation pattern.—Pinnate.         -   Leaflet color.—Developing leaflets, upper surface: Close to             N137A. Developing leaflets, lower surface: Close to 147B.             Fully developed leaflets, upper surface: Close to darker             than between 147A and N189A; venation, close to 143A. Fully             developed leaflets, lower surface: Close to 147B; venation,             close to 200B to 200C.         -   Petioles.—Length: About 18.1 cm. Diameter: About 7.5 mm.             Strength: Strong. Texture and luster, upper and lower             surfaces: Smooth, glabrous; glossy. Color, upper and lower             surfaces: Close to 146A to 146B, heavily speckled and tinged             with close to 200B to 200C. -   Flower description:     -   -   Flower shape and habit.—Single rotate flowers arranged             solitary or in panicles; freely and uniform flowering habit             with about ten flowers per inflorescence and about 70             flowers developing per plant; flowers facing outwardly to             slightly nodding.         -   Fragrance.—None detected.         -   Natural flowering season.—Plants begin flowering about ten             months after planting; plants flower during the winter in             Germany.         -   Flower longevity on the plant.—About ten days; flowers not             persi stent.         -   Flower buds.—Length: About 2.3 cm. Diameter: About 1.4 cm.             Shape: Elliptic. Texture and luster: Glabrous; matte. Color:             Close to 145D.         -   Inflorescence height.—About 29.9 cm.         -   Inflorescence diameter.—About 18.9 cm.         -   Flower diameter.—About 8.6 cm.         -   Flower depth (height).—About 2.6 cm.         -   Petals.—Transformed into nectaries.         -   Sepals.—Quantity and arrangement: About five, arranged in a             single whorl. Length: About 4.3 cm. Width: About 3.5 cm.             Shape: Broadly ovate. Apex: Obtuse. Base: Cuneate. Margin:             Entire. Texture and luster, upper and lower surfaces:             Glabrous; matte. Color: When opening, upper and lower             surfaces: Close to 155C. Fully opened, upper surface: Close             to 157B to 157C. When opening, lower surface: Close to 157C             to 157D.         -   Flower bracts.—Quantity per flower: Typically one. Length:             About 4.5 cm. Width: About 2.6 cm. Shape: Ovate. Apex:             Acute. Base: Broadly cuneate. Margin: Entire; distally,             occasionally serrated; slightly undulate. Color, upper             surface: Close to NN137A. Color, lower surface: Close to             147B; venation, close to N186C.         -   Peduncles.—Length: About 28.7 cm. Diameter: About 1.1 cm.             Aspect: About 12.5° from vertical. Strength: Strong. Texture             and luster: Glabrous; moderately glossy. Color: Close to             146C to 146D, densely speckled and flushed with close to             178A.         -   Pedicels.—Length: About 2.6 cm. Diameter: About 2.5 mm.             Aspect: About 25° from peduncle axis. Strength: Moderately             strong. Texture and luster: Glabrous; glossy. Color: Close             to 145A to 145B; proximally, finely speckled and tinged with             close to 177B to 177C.         -   Reproductive organs.—Stamens: Quantity per flower: About 70.             Filament length: About 1.8 cm. Filament color: Close to             NN155D. Anther shape: Reniform; basifixed. Anther size:             About 1.75 mm by 2 mm. Anther color: Close to 150C. Pollen             amount: Scarce. Pollen color: Close to 4D. Pistils: Quantity             per flower: About five. Pistil length: About 1.4 cm. Stigma             diameter: About 0.3 mm. Stigma shape: Club-shaped. Stigma             color: Close to 155A. Style length: About 1.375 cm. Style             color: Close to 184C to 184D. Ovary color: Close to 145A to             145B. Nectaries (transformed petals): Quantity per flower:             About 14. Length: About 1.2 cm. Diameter: About 3.5 mm.             Shape: Tubular, flattened. Texture and luster, inner             surface: Smooth, glabrous; matte. Texture and luster, outer             surface: Smooth, glabrous; glossy. Color, immature, inner             and outer surfaces: Close to 144B; towards the apex, close             to 151C to 151D. Color, mature, inner and outer surfaces:             Close to 144A; towards the apex, close to 151A to 151B;             venation, close to 146D, distally, close to 12A; with             development, color towards the apex becoming closer to 153C             to 153D.         -   Seeds and fruits.—Seed and fruit development have not been             observed on plants of the new Helleborus. -   Garden performance: Plants of the new Helleborus have been observed     to have good garden performance and to tolerate rain, wind and to be     suitable for USDA Hardiness Zones 5 through 9. -   Pathogen & pest resistance: Plants of the new Helleborus have not     been observed to be resistant to pathogens and pests common to     Helleborus plants. 

It is claimed:
 1. A new and distinct Helleborus plant named ‘COSEH 4500’ as illustrated and described. 